Localizaion of functionally different premortor neurons for the presympathetic neurons in the rostral ventrolateral medulla of rabbits.

在麻醉和固定状态下，研究了交感神经节前神经元的功能差异前运动神经元是否位于延髓吻侧腹外侧（RVLM）的不同区域。用激光或超声多普勒血流仪测量前肢和后肢肌肉、肾脏和耳皮肤的血流。通过血流和平均动脉压计算各血管床的电导。观察神经兴奋剂和神经抑制剂微注射于延髓吻侧腹外侧后对血管床电导的影响。前肢和下肢肌肉血管传导的有效区域位于RVLM的尾端，而肾脏的有效区域位于RVLM的吻端。控制皮肤血流的神经元位于RVLM的内侧。然而，这些有效区域彼此之间有相当大的重叠。由于支配前肢肌肉血管的神经节前神经元与支配耳皮肤血管的神经节前神经元位于相同的脊髓节段，我们得出结论，交感神经节前神经元的运动前神经元是根据其功能而不是轴突投射来定位的。

Whether the functionally different premotor neurons for the sympathetic preganglionic neurons are located in different area in the rostral ventrolateral medulla (RVLM) or not was studied in anesthetized and immobilized rabbits. Blood flow of muscles of a forelimb and a hind limb, kidney and skin of an ear was measured with laser or ultrasonic Doppler flow meters. Conductance of each vascular bed was calculated by the flow and the mean arterial pressure. Effects of micro-injection of neuroexcitatory or neuroinhibitory agents into the rostral ventrolateral medulla on conductance of vascular beds were investigated. The effective area for forelimb and hid limb muscle vascular conductance is localized in the caudal part of the RVLM,whereas for the kidney the effective area was located in the rostral part of the RVLM.Neurons thaht control the skin blood flow were located medial part of the RVLM.These effective areas, however, had a considerable overlap each other. Because the preganglionic neurons that innervate the vessels of the forelimb muscles are located at the same spinal segments of those innervate to vessels of the ear skin, we concluded that the premotor neurons for the sympathetic preganlionic neurons are located according to their function but not their axons projected.